⭐ Merited by OgNasty (4)
No, it's incompatible if just a few people change their behaviour. To roll out a change to the network you need to get most of the clients understanding both the old and the new protocol, and then when you have a majority you turn on the new protocol.
You just described a whole-network upgrade. I'd call that an incompatible change
The effort to raise the transaction rate limit is the same as the effort to change the fundamental nature of bitcoins: convince the vast majority to upgrade.
If we upgrade now, we don't have to convince as much people later if the bitcoin economy continues to grow.
I agree, especially since generators are both the source of blocks and "votes" in the network. Since a block restriction would allow generators to charge higher transaction fees, they might "vote" against an increase in the max size in the future.
It seems unlikely to be a real problem though.